There are now known thermal printing devices which produce labels having a length corresponding to a message to be printed as defined by a user. Such devices operate with a supply of tape arranged to receive an image and a means for transferring an image onto the tape. In one known device, a tape holding case holds a supply of image receiving tape and a supply of an image transfer ribbon, the image receiving tape and the transfer ribbon being passed in overlap through a print zone of the printing device. At the print zone, a thermal print head cooperates with a platen to transfer an image from the transfer ribbon to the tape. A printing device operating with a tape holding case of this type is described for example in EP-A-0267890 (Varitronics Inc.). In this printing device, the image receiving tape comprises an upper layer for receiving an image which is secured to a releaseable backing layer by a layer of adhesive.
In another device, the construction of the image receiving tape is such that the upper image receiving layer is transparent and receives an image on one of its faces printed as a mirror image so that it is viewed the correct way round through the other face of the tape. In this case, a double-sided adhesive layer can be secured to the upper layer, this double-sided adhesive layer having a releaseable backing layer. This latter arrangement is described for example in EP-A-0322918 and EP-A-0322919 (Brother Kogyo Kabushiki Kaisha).
Printing devices of this type also include a display means and an input means such as a keyboard for selecting characters to be printed. Selected characters are displayed on the display means and in this way a user can compose a label to be printed. When a label has been composed a print instruction is given and the printing device proceeds to print a label. Printing devices of this type also include cutting means to cut off the printed portion of the tape to enable it to be used as a label. For use as a label, the releaseable backing layer is removed from the upper layer to enable the upper layer to be secured to a surface by means of the adhesive layer. In this way, labels having a length and character arrangement determined by a user can be made.
However, the known printing devices have severe limitations as regards their ease of use in composing labels to be printed. In particular the characters displayed by the display means do not bear a relationship in terms of their size, spacing and position to the characters as will be printed out on the finished label. This makes it difficult for a user to perceive properly the final form of the label so that he must in general adopt a process where he composes a label, prints it and then reviews it to see how its format might be improved as regards character size, spacing and layout. Further, the characters displayed on the display are provided specifically for the display from a display font and thus do not resemble the characters to be printed.
The present invention seeks to overcome these difficulties in providing a printing apparatus having display means which is operable as a more useful visual aid to a user of such apparatus.
The present invention also seeks to provide a wider range of character sizes for printing and/or displaying.